Micromotor-based dual aptassay for early cost-effective diagnosis of neonatal sepsis.

Given the long-life expectancy of the newborn, research aimed at improving sepsis diagnosis and management in this population has been recognized as cost-effective, which at early stages continues to be a tremendous challenge. Despite there is not an ideal-specific biomarker, the simultaneous detection of biomarkers with different behavior during an infection such as procalcitonin (PCT) as high specificity biomarker with one of the earliest biomarkers in sepsis as interleukin-6 (IL-6) increases diagnostic performance. This is not only due to their high positive predictive value but also, since it can also help the clinician to rule out infection and thus avoid the use of antibiotics, due to their high negative predictive value. To this end, we explore a cutting-edge micromotor (MM)-based OFF-ON dual aptassay for simultaneous determination of both biomarkers in 15 min using just 2 µL of sample from low-birth-weight neonates with gestational age less than 32 weeks and birthweight below 1000 g with clinical suspicion of late-onset sepsis. The approach reached the high sensitivities demanded in the clinical scenario (LODPCT = 0.003 ng/mL, LODIL6 = 0.15 pg/mL) with excellent correlation performance (r > 0.9990, p < 0.05) of the MM-based approach with the Hospital method for both biomarkers during the analysis of diagnosed samples and reliability (Er < 6% for PCT, and Er < 4% for IL-6). The proposed approach also encompasses distinctive technical attributes in a clinical scenario since its minimal sample volume requirements and expeditious results compatible with few easy-to-obtain drops of heel stick blood samples from newborns admitted to the neonatal intensive care unit. This would enable the monitoring of both sepsis biomarkers within the initial hours after the manifestation of symptoms in high-risk neonates as a valuable tool in facilitating prompt and well-informed decisions about the initiation of antibiotic therapy.These results revealed the asset behind micromotor technology for multiplexing analysis in diagnosing neonatal sepsis, opening new avenues in low sample volume-based diagnostics.

Paper-Based Analytical Devices for Accurate Assessment of Transferrin Saturation in Diagnosed Clinical Samples from Ischemic Stroke Patients.

For the first time, a paper-based analytical device (PAD) was developed for the assessment of transferrin saturation (TSAT), which is defined as the ratio between iron bound to transferrin (Tf) and the total iron-binding capacity (TIBC) of Tf. Both parameters were simultaneously measured on the same PAD using ferrozine as a chromophore and a smartphone as the color reader. To this end, Tf was first isolated from serum using anti-Tf immunomagnetic beads to ensure that only the Tf-bound iron was measured, improving the selectivity and accuracy of TSAT assessment. To demonstrate the practical utility of the device, it was validated by analyzing a certified reference material, showing excellent accuracy (Er < 4%) and good precision (RSD ≤ 6%). Finally, 18 diagnosed serum samples from ischemic stroke patients were analyzed by this approach, and the results were compared with those obtained by urea-PAGE, showing not only an excellent correlation (r = 0.93, p < 0.05) but that the PAD approach has become statistically identical to the free-interference urea-PAGE. In comparison with the slow, tedious, and non-miniaturized-PAGE, this PAD approach exhibited attractive characteristics such as low cost, disposability, and connectivity, showing great potential for future point-of-care testing, especially in developing countries and/or remote areas, where access to medical or clinical facilities is limited.

Electrochemical sensor for the assessment of carbohydrate deficient transferrin: Application to diagnosis of congenital disorders of glycosilation.

Carbohydrate deficient transferrin (CDT) is used as biomarker of different health problems as, for example, congenital disorders of glycosylation (CDG). We propose a screen-printed-based electrochemical sensor for the determination of carbohydrate deficient transferrin using an Os (VI) tag-based electrochemistry. When transferrin is labeled with Os (VI) complex, it generates two voltammetric signals: one from carbohydrates (electrochemical signal of osmium (VI) complex at -0.9 V/Ag) and one from the amino acids present in glycoprotein (intrinsic electrochemical signal of glycoprotein at +0.8 V/Ag). The relationship between the two analytical signals (carbohydrate signal/protein signal) is an indicator of the degree of glycosylation (electrochemical index of glycosylation), which has shown an excellent correlation (r = 0.990) with the official parameter %CDT obtained by CE-UV. The suitability of this approach was demonstrated by analyzing serum samples from CDG patients.

Disposable carbon nanotube scaffold films for fast and reliable assessment of total α1-acid glycoprotein in human serum using adsorptive transfer stripping square wave voltammetry.

Alpha-1-acid glycoprotein (AGP) is a serum glycoprotein whose levels are increased two or three times during disease or injury. This makes it a potential biomarker for inflammatory bowel diseases and sepsis. Consequently, fast, simple, and cheap analytical methods for prognosis, diagnosis, and follow-up of these diseases are demanded. In this work, we propose a simple electrochemical approach based on carbon nanotubes scaffold films (CNSFs) for total AGP determination in serum samples. Firstly, AGP is labeled with an electrochemical tag (osmium(VI) complex), and then the total amount of AGP is quantified by adsorptive transfer stripping square wave voltammetry (AdTSWV). Multi-walled carbon nanotubes scaffold films (MWSFs) yielded the best analytical performance in terms of sensitivity with a good limit of detection of 0.6 mg L-1 for AGP determination in serum samples, in less than 20 min. A simplified AGP calibration and its sequential serum sample analysis strategy with good accuracy (81%) and excellent reproducibility (RSD < 1%) was additionally proposed to meet the point-of-care/needs requirements. Graphical abstract Multi-walled carbon nanotubes scaffold films for total AGP determination on disposable platforms integrating single-point calibration and sequential sample analysis.

Total α1-acid glycoprotein determination in serum samples using disposable screen-printed electrodes and osmium (VI) as electrochemical tag.

Alpha-1-acid glycoprotein (AGP) or Orosomucoid is a serum glycoprotein which belongs to the group of acute phase proteins. It is a potential biomarker for inflammatory bowel diseases. In this sense, there is a need for developing fast and cheap analytical methods for diagnosis, prognosis and follow-up of these diseases. In this work, we propose a simple and cheap electrochemical method for total AGP determination using disposable carbon screen-printed electrodes (SPE) and using a selective acidic precipitation of the rest of proteins. This method avoids the use of biological components, decreasing dramatically the analysis cost. Firstly, AGP is labeled with an electrochemical tag (osmium (VI) complex) and then the total amount of AGP is quantified by adsorptive transfer stripping square wave voltammetry. The method optimized showed a good linear correlation (r = 0.9992) and limit of detection of 1.6mgl-1. The methodology was successfully applied to quantify AGP in a commercial serum sample. This methodology could be useful in clinical diagnosis because of AGP levels increase two or three times when inflammatory processes happen. Moreover, the inherent advantages of SPE technology (low sample consumption, low cost and point of care testing) make this methodology very attractive in this field.

Gold-nanosphere formation using food sample endogenous polyphenols for in-vitro assessment of antioxidant capacity.

In this work it was demonstrated that sample endogenous polyphenols are selectively driving the gold-nanoparticle (AuNPs)-formation process when representative food samples were used as natural sources of reducing compounds. The process of AuNPs formation was characterized by UV-visible spectroscopy and was described by a sigmoidal curve (R (2) ≥ 0.990) which gave information about the polyphenol concentration at which the localized surface plasmon resonance (LSPR) absorption reached its half-value, X (c) (50) , and about AuNPs production per polyphenol concentration unit, K (AuNPs). The behavior of phenolic acids was different, with lower X (c) (50) and higher K (AuNPs) values than flavonoids. For the food samples tea, apple, pear, wine, and honey X (c) (50) values were 0.22, 7.3, 11.5, 20.4, 30.3, and 53.5 (mg mL(-1)) and K (AuNPs) values were 28.7, 0.70, 0.60, 0.20, 0.14, and 0.10 (mg(-1) mL), respectively. Excellent correlation between K (AuNPs) and total phenolics (TP) was obtained (r = 0.98, p-value < 0.05), implying K (AuNPs) is a novel marker for evaluation of food sample antioxidant capacity in vitro. The K (AuNPs) values of samples indicated their antioxidant capacity was in the order: tea > apple > pear > wine > honey. The reproducibility of the AuNPs formation approach was excellent, not only for polyphenol standards (RSD < 6 % for X (c) (50) and RSD < 11 % for K (AuNPs)) but also for food samples (RSD < 9 % for X (c) (50) and RSD < 15 % for K (AuNPs)). Transmission electronic microscopy (TEM) enabled confirmation of the formation of stabilized Au-nanospheres from endogenous polyphenols with very well-defined sizes under 20 nm diameter for all the food samples investigated.

Fast single run of vanilla fingerprint markers on microfluidic-electrochemistry chip for confirmation of common frauds.

A new strategy based on the fast separation of the fingerprint markers of Vanilla planifolia extracts and vanilla-related samples on microfluidic-electrochemistry chip is proposed. This methodology allowed the detection of all required markers for confirmation of common frauds in this field. The elution order was strategically connected with sequential sample screening and analyte confirmation steps, where first ethyl vanillin was detected to distinguish natural from adultered samples; second, vanillin as prominent marker in V. planifolia, but frequently added in its synthetic form; and third, the final detection of the fingerprint markers (p-hydroxybenzaldehyde, vanillic acid, and p-hydroxybenzoic acid) of V. planifolia with confirmation purposes. The reliability of the proposed methodology was demonstrated in the confirmation the natural or non-natural origin of vanilla in samples using V. planifolia extracts and other selected food samples containing this flavor.